Gardening Vivian | 01 May 2011 04:52 pm

Everyday Sunshine

Some Thoughts on Building Your Own Glass Green House

If you are interested in constructing a green house there a certain factors you’ll need to bear in mind if you don’t want to spend too much of your hard-earned cash. A large part of the outlay is often decided not just by the materials used and their size, but also by the way you plan to use your greenhouse; that is, its design.

A glass green house, definitely the type most extensively in use today, not only allows the largest amount of natural sunlight to reach your plants, but also allows the highest amount of heat to escape in the wintry months. The only way to get around this is to provide for extra insulation. The careful placement of a 4mm solid piece of clear plastic bolted to the inside of the green house frame should be enough to effectively reduce heat loss by 20%. Remember, it is the air space between the plastic and the glass that provides the insulation, not the plastic panel itself, so be sure to leave a wide enough gap.

The framework of a glass green house is pretty well the same as that of any greenhouse, regardless of the kind of cladding material used. Whether you use wooden, metal or plastic frame, the fundamentals of construction are more or less identical. These frames are intended to sit on a firm base with their own flooring to make working in them easier and more comfortable, and the climate easier to manage. Cheap flooring solutions can consist of anything from basic concrete slabs to timber plank-work. Whichever solution you choose, your floor doesn’t need to look too finished: this is an outhouse – a working space – not an English drawing room.

Before you start building your green house, you will want to think about those months when the climate is at its hottest. If the temperature gets too high, it will harm plants and seedlings. The same will happen in the coldest months in a non-insulated glass green house.

Some Thoughts on Heating and Ventilating your Green House

Thermostatically controlled heaters are needed to maintain your greenhouse at a constant temperature during the winter months. Electric heaters are the most the common type. This is because propane or oil heaters require the installation of an efficient ventilation system if you want to avoid stunting the growth of your plants. Furthermore, ventilation is also vital during the hottest months if you want to keep from scorching your plants. Providing good ventilation would seem to be a very good idea.

A further prerequisite for glass green houses is that they should be oriented to face east/west in order to capture the greatest amount of sunshine during the winter months. In addition, you should consider the direction of the prevailing wind. If the prevailing wind blows principally from the west, you will need to make sure your door opens to the east to avoid blasting your plants with cold air every time you go in to do a spot of gardening.

There are roof vents on the market that require no electricity, which is useful if your glass green house is a long trek from the nearest power supply. A typical system employs a simple hydraulic arm. As warmth in the greenhouse builds up, the air inside the canister of the inlet warms up causing the arm to move. This opens the vent. As the temperature drops, air inside the canister contracts and the vent closes again.

The roof form of your green house is another issue worth considering. It ought to be pitched steeply enough to avoid snow build-up and allow rain to flow freely away from the structure. You’ll need incredibly thick glass and a frame strong enough to support a brontosaurus if you try use a flat or shallow-pitched roof. A steep pitch can also make for a pleasant, airy interior, and gives you the option to place some really tall plants in the centre of your green house.

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